[OCQT Seminar] Breakdown of the Kirchhoff’s law of thermal radiation by a spatiotemporally modulated nonreciprocal metasurface

OIST Centre for Quantum Technologies (OCQT) Seminar

The OIST Center for Quantum Technologies (OCQT) is pleased to invite you to the next installment of the OCQT Seminar Series. This time, we are excited to host Dr. Diego Dalvit from Los Alamos National Laboratory (USA), who will deliver a talk entitled:
“Breakdown of the Kirchhoff’s law of thermal radiation by a spatiotemporally modulated nonreciprocal metasurface”

Date and time

Wednesday, June 10, 2026, 14:30–16:00

14:30–15:00 — Networking with coffee and sweets
15:00–16:00 — Seminar

Location

Seminar Room L5D23 (Lab 5, Level D)

Abstract

Lorentz reciprocity fundamentally limits the performance of photonic systems by enforcing reciprocal energy exchange between source and detector, formalized as a symmetric scattering matrix. In the context of thermal radiation, Lorentz reciprocity manifests as Kirchhoff’s law—the equality of the spectral directional emissivity and absorptivity of a surface.

Breaking this reciprocity is important for advancing photonic devices for energy conversion, radiative cooling and mid-infrared sensing and imaging.

Here, we report the demonstration of spatiotemporally modulated nonreciprocal metasurfaces operating at mid-infrared frequencies. We design and fabricate a graphene-based integrated photonic structure and experimentally demonstrate nonreciprocal scattering from a metasurface, modulated at gigahertz frequencies.

We further develop a theoretical framework to relate nonreciprocal scattering under spatiotemporal modulation with unequal absorptivity and emissivity, indicating a breakdown of the spectral directional version of Kirchhoff’s law of thermal radiation.

Together, our scattering experiments and theory imply effective decoupling of absorption and emission channels by breaking time-reversal symmetry at thermal wavelengths.

Biography

Diego Dalvit is a Senior Staff Member at the Theoretical Division of Los Alamos National Laboratory. He is a quantum optics theorist with expertise in quantum sensing and metrology, Casimir physics, and metamaterials.

He received his Ph.D. in Physics from Universidad de Buenos Aires (Argentina) in 1998, came to LANL in 1999 as a Director Funded Postdoctoral Fellow, and was converted to staff in 2002. He is a Fellow of the American Physical Society (APS) and Optica (former Optical Society of America), and APS Outstanding Referee. He has authored more than 120 peer-reviewed papers with >10,000 citations. He has also co-authored 5 physics textbooks on Casimir physics, thermodynamics, and statistical mechanics.

He is the holder of two patents, including one submitted in 2024 in connection to his development of the groundbreaking qCOMBPASS remote quantum sensing technology. He has helped convene more than 50 talks, seminars and related activities during his career, has held membership in committees for Los Alamos activities, and has been a reviewer for funding organizations and for publications. He has helped organized seminars, workshops and schools on quantum physics subjects, also serving as mentor to postdoctoral and graduate students over nearly three decades as a scientist.

His hobby is competitive bodybuilding.